* {
    margin: 0;
    padding: 0;
}
#box {
    margin: 50px auto 0;
    width: 400px;
    position: relative;
}
li {
    list-style: none;
    display: inline-block;
    padding: 0 10px;
    background-color: #369;
}
#xianshi {
    display: none;
    position: absolute;
    left: -50px;
    border-radius: 5px;
}
@media screen and (max-width: 770px) {
    li {
        display: block;
    }
    #xianshi {
        display: inline-block;
        background-color: rgba(222, 156, 24, .2);
        margin-bottom: 5px;
    }
    ul {
        display: none;
        animation: fadeinT 1s ;
    }
}
@-webkit-keyframes fadeinT{
    0%{opacity:0;-webkit-transform:translateY(-50px);}
    100%{opacity:1;-webkit-transform:translateY(0);}
}
@-moz-keyframes fadeinT{
    0%{opacity:0;-moz-transform:translateY(-50px);}
    100%{opacity:1;-moz-transform:translateY(0);}
}
@-ms-keyframes fadeinT{
    0%{opacity:0;-ms-transform:translateY(-50px);}
    100%{opacity:1;-ms-transform:translateY(0);}
}
@keyframes fadeinT{
    0%{opacity:0;transform:translateY(-50px);}
    100%{opacity:1;transform:translateY(0);}
}